The inventive concept relates to a semiconductor integrated circuit, and more particularly, to a liquid crystal display (LCD) panel driver having a self-masking function that utilizes a power-on reset signal, and a method of driving the same.
An LCD panel displays image data using a matrix of pixels, each located at an intersection of a gate line and a source line. Each pixel includes a liquid crystal cell that adjusts the amount of light transmission in accordance with image data, and a thin film transistor that transmits the image data from a source line to the liquid crystal cell. An LCD panel module includes a gate driver and a source driver that respectively drive the gate lines and the source lines.
FIG. 1 illustrates the power-on sequence timing of a conventional LCD panel module. Referring to FIG. 1, a first supply voltage VDD1 and a second supply voltage VDD2 output from a source driver are applied at a point in time t1. The first supply voltage VDD1 is a voltage level suitable for driving a logic circuit of the source driver, and the second supply voltage VDD2 is a high voltage level suitable for driving the source driver. Both the first supply voltage VDD1 and the second supply voltage VDD2 are stabilized at a point in time t2. A timing controller transmits image data to the source driver several frames after a reset signal RESET output from the timing controller, which controls the LCD panel module, transitions from logic low to logic high. A horizontal start pulse signal TP output from the timing controller, which drives source lines of a LCD panel, and signals output from the source driver, which correspond to the image data, are supplied at a point of time t3.
The horizontal start pulse signal TP, which controls switches that transmit the signals output from the source driver to the source lines, is configured to turn on the switches when in a logic low state. The horizontal start pulse signal TP at a low level is supplied between the time points t1 and t3 before the signals output from the source driver are supplied, and, thus, unknown signals output from the unstable source driver are transmitted to the source lines. Thus, stripes appear on the LCD panel during an initial power-on stage, causing a display failure as illustrated in FIG. 2. The display state of the LCD panel returns to a normal state at time point t3 after several tens of milliseconds.